A generalized multi-level seismic damage model for RC framed structures

A generalized multi-level damage model is developed to evaluate the seismic damage of reinforced concrete (RC) framed structures. This model is a deformation-based continuum damage model with stiffness degradation and is based on a deformation equivalent principle and generalized force-deformation relationships for concrete and its steel reinforcement. The model is called multi-level in the sense that is associated with many performance levels (e.g., immediate occupancy, life safety, collapse prevention) and structural levels (e.g., material, member, structure). Thus, it has different damage indicators for the various structural levels with specific limit values at each performance level. In order to build the correlations between the generalized damage model and the multi-level damage performance, a normalized corresponding parameter is introduced into the damage model to specify the damage limit values at each structural level. The normalized corresponding parameters are obtained by statistical analysis of results coming from finite element response calculations and tests involving 400 RC columns and 54 loading-cases of a 12-storey model frame structure. The proposed damage model is used to study evolution at various structural levels for a 12-storey model frame structure and a real tested in situ structure consisting of RC frame skeleton and masonry walls. The finite element method utilizing the proposed damage model produces results in good agreement with those of the tests.